U.S. Pat. No. 2,895,920 issued Jul. 21, 1959 to Janoski, assigned to Sun Oil Company teaches a process to prepare a catalyst for the conversion of hydrocarbons such as dehydrogenation. The catalysts comprise oxides of cobalt, iron, nickel, molybdenum, manganese, chromium, vanadium, tin, and tungsten. The catalysts do not incorporate any niobium. In the process to make the catalysts a hydrogel is prepared of metal oxide(s) which are difficult to reduce and metal oxides which are capable of existing in several oxidation states. A hydrogel of the metals is prepared and aged in the presence of hydrogen peroxide. The aged hydrogel is treated with a compound to precipitate the metals which are then filtered, dried and calcined. The sequence of treatments is different than that in the present invention.
U.S. Pat. No. 3,474,042 issued Oct. 21, 1969 to Fattore et al., assigned to Montecatini Edison S.p.A. teaches a metal oxide catalyst comprising molybdenum or tungsten. The catalysts are prepared by forming peroxy—compounds of tungsten and molybdenum, by reacting the metal oxide with hydrogen peroxide or compounds which form hydrogen peroxide. The molar ratio of peroxide to metal oxide may range from 0.25 to 10, typically from 1 to 3. The solution may be spray-dried or impregnated into a carrier.
U.S. Pat. No. 4,709,070 issued Nov. 24, 1987 to Sasaki et al., assigned to Nitto Chemical industry Co., Ltd. teaches a method to regenerate the activity of a complex metal oxide catalyst used for oxidation, ammoxidation and oxidative dehydrogenation of alkanes. The catalysts prior to reactivation are quite different from those herein. They contain a number of elements not present in the catalysts of the present invention such as Fe, Sb, Cu, and Co. The “deactivated” catalyst is treated with a Te compound, a Mo compound or a mixture thereof. The Te and Mo compounds may be oxides. In some instances the Te and Mo compounds may be prepared by contacting them with H2O2 in the presence of the oxide, oxyacid, salts of oxyacids, heteropoly acids or salts thereof of molybdenum (Col. 9 lines 38-42). The patent teaches away from treating the entire catalyst precursor and resulting catalyst with H2O2.
The supporting data for “Aiding the Self-Assembly of Supramolecular Polyoxometalates Under Hydrothermal Conditions to Give Precursors of Complex Functional Oxides”, Angewandte Chemie 201200746, Maricruz Sanchez, Frank Girgsdies, Mateusz Jastak, Pierre Kube, Robert Schlogo and Annette Trunschke (copyright Wiley—VCH 2012) teaches a hydrothermal process for making complexes similar to oxidative dehydrogenation catalysts. The components are added step wise to the autoclave apparently without reducing pressure. The addition of components is monitored by Raman spectroscopy to provide a product having a high amount of M1 phase without peroxide treatment. The reference does not suggest treating the intermediate or the final catalyst with hydrogen peroxide. Complexes produced by the process had the formula Mo1V0.2Te0.2Nb0.2Od. The reference does not teach the process or the catalysts disclosed hereinafter.
U.S. Pat. No. 8,105,972 issued Jan. 31, 2012 to Gaffney et al. from an application filed Apr. 2, 2009, assigned to Lummus Technology Inc. teaches a catalyst for the oxidative dehydrogenation of alkanes. The catalyst is formed in a conventional manner by hydrothermal treatment of metal oxide components. The resulting catalyst is recovered, dried and calcined. Then the calcined catalyst is treated with an acid. This process teaches away from the subject matter of the present invention as it teaches a post calcining treatment. Further the patent fails to teach treatment with H2O2.
The present disclosure provides an improved catalyst for oxidative dehydrogenation by treating the catalyst precursor with H2O2, prior to calcining and the resulting calcined catalyst with H2O2.